Engine stalls when wheel hits the ground

Went and picked up the motobecane today, thing didn’t start but by the end of the night got it running again, but with one problem. When taken off the stand the engine stalls and stops. Anybody have any idea why? The wheel seems to not want to spin freely on its own

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Re: Engine stalls when wheel hits the ground

Mikey Antonakakis /

Starter clutch or drive clutch is sticking

Re: Engine stalls when wheel hits the ground

That could well be, but the wheel will not spin free like a bike or a Puch unless you disengage the switch on the driven pulley, DON'T do that. It can be a real pain in the ass to re-engage. Good looking bike! :)

Re: Engine stalls when wheel hits the ground

> Mikey Antonakakis Wrote:

> -------------------------------------------------------

> Starter clutch or drive clutch is sticking

This is OP's brother and from what I can find out it seems that the clutch is seized. I can disengage the pedals from the engine with the lever near the crank and all is well so that is not sticking if that is what you are referring too when you say "Starter clutch"

Currently I'm looking for the correct tool to remove the cover and all I have found is this.

can anyone verify this will work for a moby 7 model a, av7?

Re: Engine stalls when wheel hits the ground

> Joe . Wrote:

> -------------------------------------------------------

> > Mikey Antonakakis Wrote:

>

> > -------------------------------------------------------

>

> > Starter clutch or drive clutch is sticking

>

> This is OP's brother and from what I can find out it seems that the

> clutch is seized. I can disengage the pedals from the engine with the

> lever near the crank and all is well so that is not sticking if that is

> what you are referring too when you say "Starter clutch"

>

> Currently I'm looking for the correct tool to remove the cover and all I

> have found is this.

>

> can anyone verify this will work for a moby 7 model a, av7?

Yes that is the correct puller

Re: Engine stalls when wheel hits the ground

Most excellent looking Ranger 7 - the Moby adventure has begun ! ! !

Yes - that is the puller you need for the clutch AND flywheel, you will also need that to adjust the timing which could be what it wrong. Check if the motor turns all of the time if you push the bike even at less than walking speed, might be just timing (but you will have to wait patiently for the puller to adjust it properly)

In the mean time you can check the timing and might be able to adjust it

If you are eager (or bored) I have some videos for Mobys on YouTube (sorry for the crap audio on them)

https://www.youtube.com/user/RebelMoby1/featured(edited)

Re: Engine stalls when wheel hits the ground

<3 rebel moby

Re: Engine stalls when wheel hits the ground

> Rebel Moby Wrote:

> -------------------------------------------------------

> Most excellent looking Ranger 7 - the Moby adventure has begun ! ! !

>

> Yes - that is the puller you need for the clutch AND flywheel, you will

> also need that to adjust the timing which could be what it wrong. Check

> if the motor turns all of the time if you push the bike even at less

> than walking speed, might be just timing (but you will have to wait

> patiently for the puller to adjust it properly)

Thanks those should come in handy later down the line. In the mean time I need to get that square tool to open the cover to the points.

Also as far as the clutch goes, it stayed locked no matter what. I can pedal the bike and start it but once I come to a complete stop it will stall the bike. It is not an idle problem I can tell you that.

Re: Engine stalls when wheel hits the ground

yea, can be 2 things. one is a lack of power. other is clutch.

if it's the first, it might rev but not under load

if it's clutch and all the way locked, easiest check is see how hard is it to spin the wheel with the bike off. if it's trying to turn the engine over even at low speed, like before the starter clutches should be engaging, (basically I mean spin it slow, is it dragging?)

but if it's just got no power and dies under load, that's where you gotta look at carb, airleaks, timing & compression (probably in that order)

Re: Engine stalls when wheel hits the ground

Just a FYI, the "points cover" square nut (novi nut) is reverse threaded.

Re: Engine stalls when wheel hits the ground

Also IIRC a 3/8 drive ratchet works fine for taking novi nut off in lieu of a special tool. It's in the wiki.

https://www.mopedarmy.com/wiki/Guide_to_Motobecane_spark_and_timing

Re: Engine stalls when wheel hits the ground

Use a #72 hose clamp (hardware store plumbing area near the 4 inches ABS shitter pipe) around the flywheel, brace it with a piece of 2x4 and use 3/8 a breaker bar. Novi nut is left thread so go clockwise to loose and counter clockwise to tight.

UseBreakerBar.jpg

Re: Engine stalls when wheel hits the ground

> Rebel Moby Wrote:

> -------------------------------------------------------

> Use a #72 hose clamp (hardware store plumbing area near the 4 inches ABS

> shitter pipe) around the flywheel, brace it with a piece of 2x4 and use

> 3/8 a breaker bar. Novi nut is left thread so go clockwise to loose and

> counter clockwise to tight.

> >

I use a tie down strap . But , your screw clamp seems like it would have a better 'grip' .

Re: Engine stalls when wheel hits the ground

.(edited)

Re: Engine stalls when wheel hits the ground

thanks for all the helpful replies.

The motor definitely is not super low on power. When i start it on the stand and run it its not possible to stop the rear tire (without getting hurt that is) so I am concluding that something in the dimoby is seized. I am waiting for the disassembly tools in the mail now but untill then im trying to get a good idea of the operation of the dimoby.

so far from what i can understand the centrifugal clutch arms only swing out when cranking over the motor when pedaling. I have yet to take one apart yet so im still trying to find out, How does the engine transmit power BACK to the crank pedals?

I could be all wrong on this. anything I can find on the specific part is in french

here is a video showing it idling while on the stand, a shot of the dimoby (both halves spinning while idling) and at the end i shut off the motor by holding the rear brake. https://streamable.com/n12mz

Re: Engine stalls when wheel hits the ground

I have one spare dimoby clutch hanging around. I just gave one away last week in the off topic "box exchange ". Lol. If you end up needing one feel free to PM me. You'll find that the dimoby has 2 seperate sets of centrifugal arms/pads. One is fir starting and the other set engages to your bell to transfer power to your belt. Once you get it apart it will make perfect sense.

Re: Engine stalls when wheel hits the ground

> Dusty Rim Wrote:

> -------------------------------------------------------

> I have one spare dimoby clutch hanging around. I just gave one away

> last week in the off topic "box exchange ". Lol. If you end up needing

> one feel free to PM me. You'll find that the dimoby has 2 seperate sets

> of centrifugal arms/pads. One is fir starting and the other set engages

> to your bell to transfer power to your belt. Once you get it apart it

> will make perfect sense.

wow man thanks! we'd really appreciate it, surely well discuss a price when the time comes.

Re: Engine stalls when wheel hits the ground

These are the starter clutch arms which will be exposed once you pull the cover off with your puller.

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Re: Engine stalls when wheel hits the ground

These are the primary friction pads which engage your clutch bell to transfer power to your belt and driven pulley by your pedals.(edited)

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Re: Engine stalls when wheel hits the ground

You can kill the engine with the decompression lever instead of the brake.

Re: Engine stalls when wheel hits the ground

if ya get stuck let me know im local in garbage grove

Re: Engine stalls when wheel hits the ground

I can attest, Rebel's vids are a "must watch" for anyone getting into Moby's. They'll cut the "teething pains" WAY down. I noticed in your video, your motor mount seems to be still able to hold your motor, did you replace it already? (If not) how the hell did that happen?....lol

Re: Engine stalls when wheel hits the ground

Well... now that I look more closely... you need to address that as well.

Re: Engine stalls when wheel hits the ground

Alright everybody, currently its looking like it need clutch maintenance, brake pads front and rear, new plug, headlight wiring (possibly the whole bike rewired) and motor mounts.

I did a compression test and the bike has 120psi on a quick pump and 135psi on a continuous pedal. What's considered good for these bikes?

Also this is a 1978 motobecane 7, so I will be ordering 70mm brake shoes unless someone can tell me otherwise cause from what I can tell every other mbk takes 80mm and the 7 takes 70mm

Also aslo, what is an optimal 2stroke gas mix? Correctly just to have the thing running and fixable we're using a 40:1 mixture

Re: Engine stalls when wheel hits the ground

I actually have 2 dimobys on the shelf still. This is the best of the two and its in great shape. Let me know if you need it.

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Re: Engine stalls when wheel hits the ground

Inside

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Re: Engine stalls when wheel hits the ground

Backside

Oh.. and this is a " just pay shipping and it's yours" kinda deal. ... if ya end up needing one because yours is shit.(edited)

20180111_165937.jpg

Re: Engine stalls when wheel hits the ground

Its starting to look like Im going to need it. the corrosion is unbelievable. I take whichever you're willing to give away :)

I noticed mine makes an awful lot of noise as well I don't think it was ever greased.

Re: Engine stalls when wheel hits the ground

No problemo. Pm me well make it happen. :)

Re: Engine stalls when wheel hits the ground

Ugh changing the motor mounts on a 7 is a real pain in the ass.

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